Ecuadorean villagers lend clues to longevity

CHICAGO (Reuters) - A small group of Ecuadoreans with a genetic mutation that causes dwarfism may hold clues to preventing cancer and diabetes -- two of the biggest killers in the Western world, researchers said on Wednesday.

A 22-year study of people in a remote village in Ecuador who have genetically low levels of growth hormone reveals startlingly few cases of both diseases, the international team reported in the journal Science Translational Medicine.

And drugs that are already approved to block growth hormone may help prevent these diseases, they speculate.

The team, led by Valter Longo of the University of Southern California and Jaime Guevara-Aguirre, an Ecuadorean endocrinologist, followed residents of an isolated community who had Laron syndrome.

It is a deficiency in a gene that prevents the body from using growth hormone, causing very small body size.

The team followed about 100 people with the syndrome, and 1,600 normal-sized relatives in nearby towns.

Over 22 years, there were no cases of diabetes and only one non-lethal case of cancer among the Laron group. Among the relatives, about 5 percent developed diabetes and 17 percent developed cancer.

The team believes that low levels of growth hormone played a role because both groups lived in similar environments and had similar genetic risk factors.

It is unclear how having low levels of growth hormone are protective, but prior studies of longevity in both yeast and mice have pointed to growth hormone as an important factor.

In the study, the team examined the blood of patients in the Laron group and found two differences. It protected the DNA against cancer-causing agents, and it quickly killed off any damaged cells before they could develop into cancer.

"We think that maybe this double-protective mode may very well be the reason for the lack of any cancer in this population," Longo told the briefing.

The team also found that people in the Laron group had higher levels of insulin sensitivity, which might explain how they resisted diabetes, despite somewhat higher levels of overweight and obesity.

Longo said the study suggests that using drugs to reduce high levels of growth hormone might help cut the risk of cancer and diabetes.

The Food and Drug Administration has already approved drugs that block growth hormone activity in humans to treat acromegaly, a condition related to gigantism.

"Because they are FDA-approved, there is the hope the process of testing these drugs may go much more quickly," Longo said.